president obama is on his way to south africa for tomorrow's memorial for nelson mandela. also aboard air force one are the first lady, former president george w. bush and his wife and former secretary of state hillary clinton. former presidents clinton and carter are traveling separately. mark phillips is in johannesburg. >> reporter: when the life being remembered is nelson mandela's life, even the family dances as it mourns. this is the oldest grandson and now, as oldest male, head of the mandela clan. he could only move through the crowd of dancers by joining them. he was meeting up with the rest of the family at the mandela home. they had gathered to go together to a last private viewing of the body, still being held in a military morgue, before the mandela farewell becomes a grand event. as many as 100 world leaders have said they'll attend the first and largest event of the week-long commemoration. the memorial service expected to fill the national soccer stadium. with much of the world's ruling class on hand, along with president obama, security is a huge concern a